Erosion is recognised as the greatest land degradation issue facing rural Australia. Erosion is basically the dislodgement and movement of soil from one location to another by wind or water. The Ipswich area has some of the most challenging soils in Queensland. Dispersive soils are prevalent in the area and can become a very serious issue when disturbed (e.g. during construction or land disturbance activities).
Management of exposed dispersive soils due to such activities must be considered, as these soils:
Wherever possible, the disturbance of dispersive soils should be avoided. If this is not possible, the following management options should be considered:
Damage caused by dispersive soils
The following video clip shows a site in Ipswich with highly dispersive soils. The images show the damage caused when the soils are not correctly stabilised following disturbance and the time-lapse clip shows how this soil behaves when wet.
Sediment is the soil particles collected and transported by water movement, including gravel, sand, silt and clay. Soil which is washed away goes down the storm water drain and usually ends up as sediment in local creeks and rivers. It is the sediment that causes our rivers to become brown, dirty and unhealthy. The amount of sediment entering our storm water system in Ipswich has increased as a result of land clearing and development.
The main sources of sediment in the Bremer River include:
Stirred up sediment in rivers and creeks can smother aquatic plants and impact on fish health. Other chemicals in stormwater attach themselves to sediment particles, which means that large amounts of sediment result in more chemicals in the creeks and rivers.
Sediment and erosion problems occur throughout the entire Bremer River Catchment area with the majority of sediment coming from cleared agricultural land within rural areas. However, when considering management strategies it is important to realise that urban areas contribute more than twice as much sediment per hectare during rain periods.
How to manage and control erosion and sediment in residential areas:
Sediment and erosion problems occur throughout the entire Bremer River Catchment area with the majority of sediment coming from cleared agricultural land within rural areas.
Surprisingly, large quantities of soil can be lost with erosion. One centimetre of soil lost from a one hectare surface area is equivalent to approximately 100 cubic metres of soil being removed, weighing about 100 tonnes. Losses of five to ten centimetres of top soil from many hectares are fairly common during intensive summer rain. In fact, an average ten tonnes per hectare per annum soil loss from cultivation land is considered ‘acceptable. Erosion risk is increased markedly when the soil is in a bare, cultivated condition.
Some of the ways to manage erosion and sediment include:
Large amounts of soil can be lost through erosion - a layer of soil one centimetre deep lost from an average house block is equivalent to approximately five trailer loads of soil. Erosion is worse when there is no grass, plant or mulch cover and soil is left bare. Areas of uncovered soil common when houses are being built are major contributors to this problem in urban areas.
Construction sites are very prone to erosion problems. Council is responsible for ensuring that developers and builders don’t pollute waterways. Council officers patrol the Ipswich area distributing education materials to builders, explaining what they can do to stop soil from leaving their site.
Improving erosion and sediment control (ESC) practises and compliance on construction and building sites is a practical, fair and cost-effective strategy to prevent the amount of sediment run-off and associated costs. Anyone (not just builders) who allows dirt, paint, cement or other chemicals to wash into a stormwater drain can be fined.
All erosion and sediment controls must be in accordance with International Erosion Control Association (IECA) best practice.
How to prevent erosion on house sites:
Healthy Waterways have developed an easily accessible online toolkit to help you improve erosion and sediment control compliance and reduce sediment pollution in our waterways. Visit Healthywaterways.org/esc
Adopting best-practice erosion and sediment control not only helps keep sediment pollution out of our waterways, it provides the following benefits to builders:
Further information on erosion and sediment controls can be found at Healthy Waterways.
With an ever increasing population, the Ipswich area is consistently undertaking extensive clearing of land for urban development projects. Land and infrastructure, including residential, commercial, industrial and public infrastructure developments on land are subject to legal requirements and can have a large impact on water quality in south-east Queensland. Undertaking proper erosion and sediment controls can help protect or enhance environmental values in all Queensland waterways.
All erosion and sediment controls must be in accordance with International Erosion Control Association (IECA) best practice, development approvals and site plans.
When undertaking best practice measures, it is important to include:
Should you wish to lodge a complaint improper building or other practices resulting in soil erosion or sedimentation issues visit Council's Complaints webpage and follow Council's complaints process.